There are many different forms of data recording. For example, magnetic data recording is one of the prevailing forms of data recording. Magnetic data recording may be implemented using different types of magnetic recording media, including tapes, hard discs, floppy discs, etc. Over the years, significant developments have been made to increase the areal data recording density in magnetic data recording.
Superparamagnetism is a major limiting factor to increasing magnetic recording areal density. Superparamagnetism results from thermal excitations perturbing the magnetization of grains in a ferromagnetic material, making the magnetization unstable. As the magnetic media grain size is reduced for high areal density recording, superparamagnetic instabilities become more of an issue. The superparamagnetic effect is most evident when the grain volume V is sufficiently small that the inequality KuV/kBT>40 can no longer be maintained. Ku is the material's magnetic crystalline anisotropy energy density, kB is the Boltzmann's constant, and T is absolute temperature. When this inequality is not satisfied, thermal energy demagnetizes the individual grains and the stored data bits will not be stable. Therefore, as the grain size is decreased in order to increase the areal density, a threshold is reached for a given material Ku and temperature T such that stable data storage is no longer feasible.
The thermal stability can be improved by employing a recording medium formed of a material with a very high Ku. However, the available recording heads are not able to provide a sufficiently high enough magnetic writing field to write on such a medium. Heat Assisted Magnetic Recording (HAMR), sometimes referred to as optical or thermal assisted recording, has been proposed to overcome at least some of the problems associated with the superparamagnetic effect. HAMR generally refers to the concept of locally heating a recording medium with a laser to reduce the coercivity of the recording medium, so that an applied magnetic writing field can more easily direct the magnetization of the recording medium during the temporary magnetic softening of the recording medium caused by the laser. By heating the medium, the Ku or the coercivity is reduced such that the magnetic write field is sufficient to write to the medium. Once the medium cools to ambient temperature, the medium has a sufficiently high value of coercivity to assure thermal stability of the recorded information.
Current proposed HAMR head designs uses an optical fiber to couple the light from the laser to the recording head. The head integrates a waveguide for facilitating coupling the light from the laser onto the recording medium. Certain current HAMR head designs require that the head, which is supported at one end of a slider, to have a sufficiently large back surface area in order to accommodate coupling of the light from the laser, which competes for space with the bonding pads (not shown) for external electrical leads to the head. Further, precise alignment of the fiber to the head is required. For example, as shown in FIGS. 1A and 1B, one current design of HAMR head 20 uses a diffraction grating 10 on the back of the slider 12 to couple light into a waveguide 14 in the slider. The grating 10 is exposed to external of the HAMR head 20. In order for this design to work, the angle of the fiber 16 with respect to the normal of the grating 10 has to be precisely maintained at the designed angle. The head can further include a solid immersion mirror (SIM) (not shown) for focusing radiant energy. In order for proper coupling with the grating 10, and proper focusing within the SIM, the beam 18 from the fiber 16 has to be precisely centered on the grating, and at the designed angle θ. Therefore, during the assembly of the slider to the suspension assembly, the fiber and the head will have to be aligned to very exact tolerances. Further, the fiber and the head must maintain these tolerances during the lifetime of the drive.
Accordingly, there is a need for a support for precise coupling of radiant energy from a fiber to a HAMR head. It is also desirable that this support minimizes coverage of the surface area on the back of the slider to make room available for bonding pads.